The number of biliary tract cancer (gallbladder cancer and cholangiocarcinoma) deaths is on the rise in Japan, and 16,586 people died of the cancer in 2005. In most biliary tract cancer cases, no subjective symptoms are present in the early stages. Compared to cancers that form on the inside of the digestive tract, such as stomach cancer and colon cancer, accurate visualization and diagnostic imaging of biliary tract cancer is difficult. Therefore, early detection of biliary tract cancer is difficult, and the cancer has often already progressed and is unresectable when it is found. Besides surgical therapy, radiation therapy and chemotherapy are performed for treatment of biliary tract cancer, but they are not therapeutically effective, and thus the establishment of new therapeutic methods is urgently needed.
Lung cancer deaths are also on the rise in Japan, and 62,063 people died of the cancer in 2005. At present, lung cancer accounts for 19.0% of the cancer deaths in Japan, and it has been the leading cause of cancer death since 2000. Smoking is said to be the main cause of the onset of lung cancer. Besides smoking, inhalation of asbestos or radon gas is also believed to cause lung cancer. Smoking cessation is encouraged and health checks are carried out as measures to prevent lung cancer. However, although it is decreasing, the smoking population in Japan in 2005 is still estimated to be approximately 30 million. Furthermore, recently, it has been shown that simple chest X-ray imaging and sputum test widely performed during health checks are not effective for early detection of lung cancer, and thus they do not lead to reduction of cancer deaths. Considering the above, the number of lung cancer deaths is predicted to continue increasing in the future.
The symptoms of lung cancer include cough, bloody sputum, shortness of breath, and chest pain, but in most cases, symptoms are absent in the early stages. When symptoms appear, the cancer has already progressed in many cases. Therefore, more than half of the patients are inoperable when the cancer is first discovered, and it is regarded as one of the intractable cancers. The recovery rate after operation is not as good as other cancers, and the overall five-year survival rate after surgery is just short of 50%. In recent years, the five-year survival rate for early-stage lung cancer is increasing as a result of advances in multimodal treatment by radiotherapy, chemotherapy, and such with surgical resection as the main treatment; however, improvement of the therapeutic effects for advanced lung cancer is poor, and the establishment of new therapeutic strategies is in urgent need.
The number of pancreatic cancer deaths is also on the increase in Japan, and 22,927 people died of the cancer in 2005. At present, pancreatic cancer accounts for 7.0% of the cancer deaths in Japan, and ranks fifth following lung cancer, stomach cancer, colon cancer, and liver cancer. There are no symptoms specific to pancreatic cancer, and in many cases when symptoms appear, the cancer has already progressed. Even today with advances in diagnostic imaging, approximately 40% of total Japanese pancreatic cancer patients belong to advanced cases with distant metastasis, and many patients are found to have unresectable locally-advanced cancer. Therefore, the overall five-year survival rate of the patients is 5% or less, and the prognosis after diagnosis is very poor. Due to the difficulty in diagnosis, the incidence of pancreatic cancer as a cause of cancer death is gradually increasing particularly in advanced countries. Although multimodal treatment by radiotherapy, chemotherapy, and such with surgical resection as the central treatment is presently carried out, there is no dramatic improvement in the therapeutic effects, and the establishment of novel therapeutic strategies is urgently needed. Various factors such as lifestyle habits including smoking, obesity, diet, alcohol drinking, and coffee drinking, as well as chronic pancreatitis, diabetes, genetic factors, and such have been suggested to be involved in causing the onset of pancreatic cancer.
On the other hand, recent development in molecular biology and tumor immunology has elucidated that cytotoxic (killer) T cells and helper T cells recognize peptides generated by degradation of proteins that are specifically and highly expressed in cancer cells and which are presented on the surface of cancer cells or antigen presenting cells via HLA molecules, and cause immunoreaction to destroy cancer cells. Furthermore, many tumor antigen proteins and peptides derived therefrom, which stimulate such immunoreaction to attack cancer, have been identified, and antigen-specific tumor immunotherapy is being clinically applied.
The HLA class I molecule is expressed on the surface of all nucleated cells of the body. It binds to a peptide generated by intracellular degradation of proteins produced in the cytoplasm or nucleus, and expresses the peptide on the cell surface. On the surface of a normal cell, peptides derived from normal autologous proteins bind to HLA class I molecules, and are not recognized and destroyed by T cells of the immune system. On the other hand, in the process of becoming a cancer, cancer cells sometimes express a large quantity of proteins that are hardly or slightly expressed in normal cells. When HLA class I molecules bind to peptides generated by intracellular degradation of proteins specifically and highly expressed in cancer cells, and then express the peptides on the surface of cancer cells, killer T cells recognize and destroy only the cancer cells. By administering such cancer-specific antigens or peptides to an individual, cancer cells can be destroyed and cancer growth can be suppressed without harming normal cells. This is called cancer immunotherapy using cancer-specific antigens. HLA class II molecules are mainly expressed on the surface of antigen-presenting cells. The molecules bind to peptides derived from cancer-specific antigens, which are generated by intracellular degradation of cancer-specific antigens incorporated into antigen-presenting cells from outside of the cells, and then express the peptides on the surface of the cells. Helper T cells that recognize them are activated, and induce or enhance immunoreaction against tumors by producing various cytokines that activate other immunocompetent cells.
Accordingly, if an immunotherapy that targets antigens specifically and highly expressed in cancers is developed, such a therapy can effectively eliminate cancers alone without causing any harmful event on normal autologous organs. It is also expected that the therapy can be used for any terminal cancer patients to whom other treatments cannot be applied. In addition, by administering a cancer-specific antigen and peptide as a vaccine in advance to individuals with a high risk of developing cancers, cancer development can be prevented.
The present inventors first conducted genome-wide gene expression analysis on 27,648 human genes using cDNA microarrays to investigate the expression profiles of these genes in 25 intrahepatic bile duct cancer cases and in various normal organs including those in the embryonic stage. As a result, the present inventors discovered that Forkhead box m1 (FOXM1) (GenBank Accession No. NM_202003) was very highly expressed in the tissues of many intrahepatic bile duct cancer cases. Similar to and in addition to intrahepatic bile duct cancer, FOXM1 was found to be highly expressed in almost all the cases of lung cancer, bladder cancer, and pancreatic cancer. Furthermore, high expression of FOXM1 was found in 40% or more of the cases in a wide variety of cancers such as cervical cancer, ovarian cancer, malignant lymphoma, breast cancer, stomach cancer, esophageal cancer, prostate cancer, hepatocellular carcinoma, colon cancer, and chronic myeloid leukemia. These facts suggest that FOXM1 could serve as a cancer-specific antigen in various cancers. FOXM1 is expressed in embryonic liver, and in normal adult organs, it is slightly expressed in the digestive tract such as stomach, small intestine, and large intestine, thymus, and testis; however, the expression level is remarkably low compared to cancerous parts.
Examples of the documents indicating that FOXM1 is related to the onset of cancer and the regulation of cell proliferation include Non-patent Documents 1 to 10. However, none of the documents describes the use of FOXM1 as a vaccine against cancer.
[Non-patent document 1] Yoshida Y, Wang I-C, Yoder H M, Davidson N O, Costa R H.: The forkhead box M1 transcription factor contributes to the development and growth of mouse colorectal cancer. Gastroenterology 132: 1420-1431, 2007.
[Non-patent document 2] Gusarcova G A, Wang I-C, Major M L, Kalinichenko V V, Ackerson T, Petrovi V, Costa R H.: A cell-penetrating ARF peptide inhibitor of FOXM1 in mouse hepatocellular carcinoma treatment. J. Clin. Invest. 117: 99-111, 2007.
[Non-patent document 3] Radhakrishnan S K, Bhat U G, Hughes D E, Wang I-C, Costa R H, Gartel A L.: Identification of a chemical inhibitor of the oncogenic transcription factor forkhead box M1. Cancer Res. 66: 9731-9735, 2006.
[Non-patent document 4] Takahashi K, Furukawa C, Takano A, Ishikawa N, Kato T, Hamaya S, Suzuki C, Yasui W, Inai K, Sone S, Ito T, Nishimura H, Tsuchiya E, Nakamura Y, Daigo Y.: The neuromedin U-growth hormone secretagogue receptor 1b/neurotensin receptor 1 oncogenic signaling pathway as a therapeutic target for lung cancer. Cancer Res. 66: 9408-9419, 2006.
[Non-patent document 5] Kim I-M, Ackerson T, Ramakrishna S, Tretiakova M, Wang I-C, Kalin T V, Major M L, Gusarova G A, Yoder H M, Costa R H, Kalinichenko V V.: The forkhead box m1 transcription factor stimulates the proliferation of tumor cells during development of lung cancer. Cancer Res. 66: 2153-2161, 2006.
[Non-patent document 6] Wonsey D R, Folletie M.: Loss of the forkhead transcription factor FoxM1 causes centrosome amplification and mitotic catastrophe. Cancer Res. 65: 5181-5189, 2005.
[Non-patent document 7] Obama K, Ura K, Li M, Katagiri T, Tsunoda T, Nomura A, Satoh S, Nakamura Y, Furukawa Y: Genome-wide analysis of gene expression in human intrahepatic cholangiocarcinoma. Hepatology 41: 1339-1348, 2005.
[Non-patent document 8] Laoukili J, Kooistra M R H, Bras A, Kauw J, Kerkhoven R M, Morrison A, Clevers H, Medema R H.: Foxml is required for execution of the mitotic programme and chromosome stability. Nature Cell Biol. 7: 126-136, 2005.
[Non-patent document 9] Kalinichenko V V, Major M, Wang X, Petrovic V, Kuechle J, Yoder H M, Shin B, Datta A, Raychaudhuri P, Costa R H.: Foxmlb transcription factor is essential for development of hepatocellular carcinomas and is negatively regulated by the p19ARF tumor suppressor. Genes Dev. 18: 830-850, 2004.
[Non-patent document 10] Wang X, Kiyokawa H, Dennewitz M B, Costa R H.: The forkhead box m1b transcription factor is essential for hepatocyte DNA replication and mitosis during mouse liver regeneration. Proc. Natl. Acad. Sci. USA 99: 16881-16886, 2002.